Joint USAF/NOAA Report of Solar and Geophysical Activity 11 September 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Sep 11 2200 UTC
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
# Space Weather Prediction Center and the U.S. Air Force.
#
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 254 Issued at 2200Z on 11 Sep 2011
IA. Analysis of Solar Active Regions and Activity from 10/2100Z
to 11/2100Z: Solar activity was low. Region 1283 (N14W87) produced
a long duration C6/Sf flare at 11/0851Z. Region 1283 currently is
rotating around the west limb as a Dso spot group with a Beta-Gamma
magnetic classification. Region 1289 (N22E12), a Dko-Beta spot
group with 430 millionths in area, exhibited decay in its smaller
trailing spots. New Region 1292 (N08E66) was numbered today.
IB. Solar Activity Forecast: Solar activity is expected to continue
at low levels with further M-class flares likely on 12 September as
Region 1283 continues to rotate around the west limb. On 12 – 14
September, solar activity is expected to be at low levels with a
slight chance for M-class flares.
IIA. Geophysical Activity Summary 10/2100Z to 11/2100Z:
The geomagnetic field was at quiet to minor storm conditions. Minor
storm levels were observed during the period 10/2100 – 2400Z.
Activity was likely due to continued CME effects followed by a
coronal hole high speed stream. At approximately 10/1401Z, a slight
increase in density, wind speed, and temperature was seen in the ACE
solar wind monitor. Solar wind speed continued to increase to
approximately 660 km/s while density dropped to around 1 p/cc during
the period. This was most likely the start of the transition into
the coronal hole high speed stream.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be unsettled to active with minor storm periods possible
on days 1 and 2 (12-13 September) due to continued coronal hole
influence and a possible glancing blow from the 10 September CME.
Conditions are expected to be quiet to unsettled on day 3 (14
September).
III. Event Probabilities 12 Sep-14 Sep
Class M 55/35/35
Class X 05/01/01
Proton 05/01/01
PCAF Green
IV. Penticton 10.7 cm Flux
Observed 11 Sep 121
Predicted 12 Sep-14 Sep 120/115/115
90 Day Mean 11 Sep 100
V. Geomagnetic A Indices
Observed Afr/Ap 10 Sep 020/033
Estimated Afr/Ap 11 Sep 010/018
Predicted Afr/Ap 12 Sep-14 Sep 010/012-010/012-005/008
VI. Geomagnetic Activity Probabilities 12 Sep-14 Sep
A. Middle Latitudes
Active 20/20/05
Minor storm 10/10/01
Major-severe storm 05/05/01
B. High Latitudes
Active 30/30/15
Minor storm 10/10/05
Major-severe storm 05/05/01